The present invention is directed toward the in situ conversion and subsequent recovery of heavy hydrocarbonaceous crude oil. Although conventional crudes may be recovered by pumping and subsequent enhanced oil recovery procedures, the heavier crude oils which have been discovered resist the heretofore conventional techniques utilized for recovery. In any case, the recovery of crude oil is never complete and the utilization of conventional techniques for heavy crude recovery is even more bleak. For example, some of the heaviest crude oil deposits have a conventional recovery rate of approximately 5 percent. Moreover, such a heavy oil requires substantial processing in order to yield useful products.
Therefore, in order to recover greater quantities of the heavier crude oil, I propose to convert these crudes in situ with a combination of high temperature and high pressure hydrogen and to recover lighter and therefore more easily recoverable crude oil. In addition, many of the heavier crudes contain indigenous trace quantities of metals which may be made to perform a catalytic function in the conversion of the hydrocarbons to more valuable products. Such metals include nickel, vanadium, iron, etc. These metals may occur in a variety of forms. They may exist as metal oxides or sulfides introduced into the crude oil as metallic scale or similar particles, or they may exist in the form of water-soluble salts of such metals. Usually, however, they exist in the form of stable organometallic compounds, such as metal porphyrins and the various derivatives thereof.
In addition to organometallic compounds, crude oils contain greater quantities of sulfurous and nitrogenous compounds than are found in lighter hydrocarbon fractions. For example, a heavy Venezuela crude also known as Orinoco Tar, having a gravity of 9.9.degree. API at 60.degree. F., contains about 1260 ppm vanadium, 105 ppm nickel, 11 ppm iron, 5.88 weight percent sulfur and about 0.635 weight percent nitrogen. Reduction in the concentration of the sulfurous and nitrogenous compounds, to the extent that the crude oil is suitable for further processing, is accomplished by conversion to hydrogen sulfide and ammonia.
I have discovered a method to maximize the utilization of hydrogen during the in situ conversion and recovery of heavy hydrocarbonaceous crude oil.